This is a double-blind, phase I/II, placebo-controlled ACTG study that will evaluate the safety and immunogenicity of a seven valent pneumococcal conjugate vaccine. Streptococcus pneumoniae causes serious infections in humans, such as pneumonia, meningitis, sepsis, and arthritis. This organism also causes more common, but less severe infections, such as otitis media and sinusitis. Adults with human immunodeficiency virus infection are recognized to be at high risk for severe pneumococcal infection. Children with HIV infection have a high incidence of bacterial pneumonia, otitis media and sinusitis, a large fraction of which are likely to be caused by pneumococcus. It has recently been recognized that children with HIV infection are at increased risk for invasive pneumococcal infection, particularly bacteremia. This trial proposes a polyvalent conjugate vaccine directed against those pneumococcus serotypes that are responsible for up to 90% of invasive disease in these children.